1. Field of the Invention
The present invention relates to reversible photoligating nucleic acids and phosphoramidites. More specifically, the present invention relates to a novel reversible photoligating nucleic acid which can be useful in its application to antisense DNA, antigene DNA, photogenetic diagnostic therapy, and in the analysis of DNA-protein interaction and the like, and can be used to control the formation and specific cleavage of ligation structures in biofunctional molecules using light; the present invention also relates to phosphoramidites useful for the synthesis of such nucleic acids, as well as methods of photoligation and photocleavage wherein such nucleic acids are used.
2. Description of the Related Art
It has been known that controlling the ligation and local cleavage between DNAs, RNAs, PNAs and proteins is important in determining biofunctions and the mechanism of bioactivities, as well as in creating bioactive substances.
For example, controlling the formation and the cleavage of the ligation structures of DNA-DNA, DNA-RNA, DNA-PNA or DNA-protein is very important in elucidating antisense DNAs, antigene DNAs, and genetic diagnostic therapy, and in determining the interactions between DNA-protein, as well as in controlling the structure of biomolecules accordingly.
Therefore, many means for ligation and cleavage have been studied, and methods involving photoirradiation are being investigated, as well.
However, the methods reported so far have problems such as the lowness of ligation product yield of about 40%, and the generation of various by-products. Further, examples of methods wherein the ligated sites are specifically cleaved have not been known.
Accordingly, the object of the present invention is to provide solutions to the above-described problems of the conventional methods, and to provide a novel technical means that gives selective high ligation product yield and selective photocleavage of the ligated site, and enables the free and reversible control of photoligation and photocleavage.
The present invention provides, as a means to solve the aforesaid problems, firstly, a reversible photoligating nucleic acid represented by the following formula (1): 
Also, secondly, a phosphoroamidite represented by the following formula (2): 
is provided.
Further, the present invention provides, thirdly, a method of photoligation, wherein a system containing the above reversible photoligation nucleic acid and a biofunctional polymer is irradiated to form a ligation structure. Fourthly, a method of photocleavage, wherein the ligated structure formed between a reversible photoligating nucleic acid and a biofunctional polymer is cleaved by the irradiation of light with short wavelength is provided.
By irradiating the above-described reversible photoligating nucleic acid of the present invention, i.e. a DNA containing photoligating nucleoside, 1) the ligation and cleavage of DNA-DNA, DNA-RNA, DNA-PNA and DNA-protein is enabled, and uses in a) antisense DNA, b) antigene DNA, c) photogenetic diagnostic therapy, and d) analysis of DNA-protein interaction may be developed.
Furthermore, according to the present invention, high ligation products yield of 95% or higher is obtained, and the ligated site-specific cleavage by irradiation is also enabled.